1. Field of the Invention
The present invention relates to a latch device which moves a latch body to an inserted state position and a withdrawn state position in a housing.
2. Description of the Related Art
FIG. 19 is a perspective view showing a conventional latch device 170. In FIG. 19, the latch device 170 includes a housing 110, and the housing 110 accommodates a latch body 112 which is urged by a compression spring 122 in a direction of being withdrawn from the housing 110. A rectangular frame 116 is formed at one longitudinal end of the housing 110. An opening 114 is provided in an end of the rectangular frame 116, and the latch body 112 is inserted in the opening 114. Unillustrated projections extend from both side surfaces of the housing 110, and a mounting plate of an unillustrated audio apparatus or the like is clamped by the projections and the rectangular frame 116 so as to mount the housing 110 to the mounting plate.
A concave portion 130 is provided a top surface 126 and an unillustrated bottom surface of the latch body 112, respectively. A circulatory cam groove 166 is formed in each of the concave portions 130. Further, a cam 168 including an engaging concave portion 168A is formed in each of the concave portions 130. An outer peripheral surface of the cam 168 forms a part of the circulatory cam groove 166.
In the latch device 170, a tracing member 160 is provided to correspond to the circulatory cam groove 166. The tracing member 160 is provided in a substantially rectangular form. The tracing member 160 horizontally extends from both ends of a supporting portion 161 in the same direction, and distal ends thereof are bent at right angles in a mutually approaching direction so as to form tracing portions 162 and 164. The tracing portion 162 is guided by an outer periphery of the cam 168 which is formed on the top surface of the latch body 112. Further, the tracing portion 164 is guided along an outer periphery of the unillustrated cam 168 which is formed on the reverse surface of the latch body 112.
A pair of arms 146, 148 are provided at an end of the latch body 112 which is opposite to the end thereof which is inserted into the housing 110. The respective distal ends of the arms 146, 148 are separated from each other so that the pair of arms 146, 148 are provided in an enlarged diameter state.
In the latch device 170, an enlarged diameter distal portion 150A of a striker 150 provided at an unillustrated openable cover presses an intermediate portion 147 provided between the arms 146 and 148 so as to push the latch body 112 in an inner direction of the housing 110. Consequently, the arms 146, 148 contact the rectangular frame 116 so that the arms 146, 148 rotate in a mutually approaching direction with hinges 146A, 148A as fulcrums. As a result, the enlarged diameter distal portion 150A of the striker 150 is held by the arms 146, 148, thereby closing the openable cover.
At this time, the tracing portions 162, 164 of the tracing member 160 are guided by the respective outer peripheries of the cams 168 corresponding thereto so as to reach the engaging concave portions 168A. Further, the tracing portions 162, 164 engage the engaging concave portions 168A to prevent the latch body 112 from being withdrawn from the housing 110.
However, in the prior art latch device, the circulatory cam grooves 166 are provided in the latch body 112. Accordingly, it is necessary to provide a thick-walled latch body 112 so as to ensure the strength of a position of the latch body 112 which becomes thinner due to the circulatory cam groove 166. As a result, it is difficult to make the latch body 112 more compact and thinner. Further, there are drawbacks in that the configuration of the latch body 112 is complicated and molding failure easily occurs due to the circulatory cam grooves 166 which are provided in the latch body 112.
In addition, if the circulatory cam grooves 166 are area in the latch body 112, there are thin-walled positions of the latch body 112 due to the circulatory cam grooves 166. Thus, it is impossible to efficiently ensure rigidity of the latch body 112, and it is difficult to efficiently ensure reliable operation of the latch device.
As shown in FIG. 20, there is another well-known conventional latch device used to anchor, for example, the openable cover of an audio apparatus or the like. In the latch device, a latch body 202 is inserted into an opening 200A of a housing 200 which is attached to the audio apparatus or the like. An engaging portion 206 is formed via a hinge portion 204 at an end of the latch body 202 in a withdrawn direction (i.e., in a direction of arrow H in FIG. 20). The engaging portion 206 includes engaging pawls 206A and 206B to hold the openable cover.
Further, in the latch device, a tracing member 210 is accommodated in a concave portion 208 which is provided in the latch body 202, and a rotary shaft 212 of the tracing member 210 is inserted into a through hole 200B of the housing 200. Therefore, when a tracing portion 214 circulates and moves in a circulatory cam groove 218 provided in the latch body 202 as shown in FIG. 21, the tracing member 210 can rotate in a direction perpendicular to the surface of the drawings of FIG. 20 about the rotary shaft 212.
As shown in FIG. 21, the circulatory cam groove 218 is provided in a substantially heart-shaped form, and a projection 216 is provided at an intermediate portion thereof. Further, the circulatory cam groove 218 is positioned such that a groove concave portion 218A and a groove distal end 218B can respectively anchor the tracing portion 214 in an inserted state and a withdrawn state of the latch body 202.
In this case, when the engaging pawl 206B of the engaging portion 206 shown in FIG. 20 is pressed via the unillustrated openable cover in an inserted direction (i.e., in a direction of arrow I in FIG. 21), the latch body 202 is moved in the inserted direction. Accordingly, the tracing portion 214 of the tracing member 210 is moved relatively from the groove concave portion 218A in a direction of arrow J in FIG. 21 via a step portion 220 to a groove top portion 218C. When the pushed-in operation of the latch body 202 is released, the latch body 202 is moved in the withdrawn direction by urging force of the compression coil spring 224 shown in FIG. 20. Thus, the tracing portion 214 is moved in a direction of arrow K, and is moved relatively to the groove distal end 218B via the step portion 226. The latch body 202 is thereby withdrawn from the housing 200 (the state shown by the solid lines in FIG. 20). When the latch body 202 is switched over from the inserted state to the withdrawn state, the hinge portion 204 is deformed by the urging force of the compression coil spring 224 to rotate the engaging portion 206 of the latch body 202 counterclockwise from its horizontal position shown by the imaginary lines in FIG. 20. The holding state of the openable cover is thereby released.
When the latch body 202 in the withdrawn state is pushed in the inserted direction again, the tracing portion 214 is moved in a direction of arrow L from the groove distal end 218B to a groove top portion 218D of the circulatory cam groove 218 via a step portion 228. When overstroke in the pressing operation is canceled, the latch body 202 is moved in the withdrawn direction by the urging force of the compression coil spring 224. Consequently, the tracing portion 214 is moved from the top portion 218D in a direction of arrow M, and is moved to the concave portion 218A via a step portion 230, resulting in a pushed-in state where the latch body 202 is pushed into the housing 200 (see the imaginary lines in FIG. 20). When the latch body 202 is switched over from the withdrawn state to the pushed-in state, the hinge portion 204 is deformed against the urging force of the compression coil spring 224 so as to rotate the engaging portion 206 clockwise from the state shown by the solid lines in FIG. 20. The engaging portion 206 is thereby set in the horizontal state shown by the imaginary lines.
However, in the conventional latch device, the hinge portion 204 is deformed so as to rotate the engaging portion 206 for each pressing operation of the openable cover. Therefore, it is impossible to provide sufficient durability of the hinge portion since the hinge portion is fatigued by each pressing operation. In order to overcome this drawback, there is another latch device in which the engaging portion 206 is coupled with respect to the latch body 202 by a pin, and the engaging portion 206 is rotatable about the pin. However, in this latch device, there are other drawbacks such as the number of component parts is increased due to the pin, and manufacturing process of the latch device is more complicated.